1. Field of the Invention
The present invention relates to hydraulic systems used for operating elements on an aircraft and, more particularly, to hydraulic systems including a high-pressure differential cylinder and a valve combination hydraulically connected thereto.
2. Description of Prior Art
In the construction of an aircraft, especially in an aircraft having multiple jets, many servo actuators are needed. Each servo actuator is needed for operating particular aircraft systems such as wing components, spoilers, landing gear doors and many other systems of the aircraft. Each actuator is a small hydraulic system using a high pressure cylinder. A valve combination using an electro-hydraulic servo valve (EHSV) is needed to allow operation of these cylinders in different manners in accordance with different guidelines and conditions. The valve combination is normally connected to additional individual valves which allow for performance of other operating states in addition to the normal operating state.
For example, when operating a spoiler, which functions as a lift destroyer, a speed brake and a roll controller, an actuator which is able to operate in numerous modes is needed. These modes include a normal operating mode, a blocking mode at reduced system pressure, a thermal relief mode, a maintenance mode, and a mode for operating after detection of an hydraulic supply malfunction or electrical control signal error. For operating in all of these modes a combination of multiple individual valves is required. These individual valves are linked to the electro-hydraulic servo valve and are controlled for operating in each of the aforementioned modes.
The actuator and valve combinations needed for proper operation of an aircraft are large in size and high in weight due to the many individual valves needed for proper operation of the device. Because many of these devices are needed for controlling the various systems of an aircraft, the excess size and weight of each device is multiplied when all the devices are taken as a whole.
It is, thus, desirable to provide an hydraulic system in which the multiple individual valves are combined into a compact, lightweight, multi-functional valve. It would also be desirable to provide a housing in which the valve is arranged and wherein the correcting elements lie along a functional axis within the housing thereby reducing the size and improving the functionality of the device.